REU: Effects of Resource Quality and Microarthropods on Forest Floor Nitrogen Dynamics

资源质量是一个主要因素控制率 森林有机质分解与养分释放 生态系统 在资源质量和 微气候、分解和养分动态是 微生物与动物的相互作用 微型节肢动物活动 一般增加落叶分解率，数据 表明，增强外源氮固定。 本项目的目标是研究 分解者群落和森林地面的资源质量 N通量，使用15 N作为示踪剂，并进行更详细的研究 微型节肢动物活动对氮素迁移的影响。 实地实验将检查资源质量的影响 （1）~（15）N标记凋落物N净矿化量 （2）释放的~（15）N在森林中的迁移 地面剖面（凋落物N，F层N，土壤活性（微生物）N， 土壤慢/被动N和土壤可提取N）;（3）固定化 15 N标记的外源输入和随后的矿化， 土壤氮素的真菌转移 以15 N为示踪剂，对表层凋落物进行了示踪研究。 在即将完成的研究中， 微型节肢动物从腐烂的基质中产生了一种 显著影响分解速率和氮保留率。 的 这种影响的机制将在更多的章节中详细研究。 控制条件，通过直接操纵微型节肢动物 在实验室培养中，通过测量 微节肢动物-微生物相互作用的影响：（1） 微生物现存量和总异养呼吸， (2)15 N标记枯枝落叶层中N的矿化;（3） 15 N标记的外源输入的固定化。 这个研究小组一直表现出卓越的 和生产力。 机构的住宿条件是一流的。 这项研究的成果应该是重要的，更好地 森林资源的管理以及森林资源的基本 了解森林生态系统。

Resource quality is a major factor controlling rates of organic matter decomposition and nutrient release in forested ecosystems. Within the constraints of resource quality and microclimate, decomposition and nutrient dynamics are the product of faunal-microbial interactions. Activities of microarthropods generally increase decomposition rates of leaf litter and, data suggest, enhance immobilization of exogenous nitrogen. The objectives of this project are to examine the effects of resource quality on the decomposer community and on forest floor N fluxes, using 15N as a tracer, and to examine in more detail the effects of microarthropod activities on nitrogen movement. Field experiments will examine the influence of resource quality on (1) net mineralization of N from 15N-labeled litter substrates, (2) the movement of released 15N through the forest floor profile (litter N, F-layer N, soil active (microbial) N, soil slow/passive N, and soil extractable N); (3) immobilization of 15N-labeled exogenous inputs and subsequent mineralization and movement, and (4) fungal translocation of N from the soil horizon to surface litter using 15N as a tracer. In research now nearing completion, exclusion of microarthropods from decaying substrates has produced a significant effect on decomposition rates and N retention. The mechanisms for this effect will be examined in detail under more controlled conditions, by directly manipulating microarthropods in laboratory incubations, and by measuring the quantitative effects of microarthropod-microbial interactions on: (1) microbial standing stocks and total heterotrophic respiration, (2) mineralization of N from 15N-labeled litter and (3) immobilization of 15N-labeled exogenous inputs. This research group has demonstrated consistent excellence and productivity. Institutional accommodations are first-rate. Products of this research should be of importance to the better management of forest resources as well as to the fundamental understanding of forested ecosystems.